1. Field of the Invention
The present invention generally relates to a forging device and a method for forging a work, and more particularly relates to a forging device suitable for forging a work having one or more teeth circumferentially and a forging method using the forging device.
2. Description of Related Art
A typical forging device has a clamp in a die section placed on a base to clamp a circular die. For example, the circular die has inner teeth along its internal surface for shaping gear teeth. A work is positioned at an upper portion of the die. The work is prepared for shaping a gear and having rough teeth along its outer surface. A punch presses the work downward from its top end to push it into the die so that the inner teeth of the die shape relatively fine gear teeth from the rough ones. For example, JP-A-2005-7468 discloses such a forging device.
The forging device, however, causes difficulty in highly accurately shaping the gear teeth, because the work is only pressed from the top end thereof. That is, a pressure given to the work is not uniform, and the pressure at the end pressurized by the punch is higher than the other end. In other words, the pressure is the highest at the top of the work and reduces toward the bottom of the work. Particularly, in shaping a helical gear, the accuracy can further deteriorate because pressures on both lateral sides of the gear are different from each other in addition to the imbalance of the pressure discussed above.
Thus, an improved forging device or forging method is required to more accurately shape a product having meshing teeth such as, for example, a gear, serration, spline or the like.